1. Field of the Invention
The present invention relates to a pneumatic tire and noise damper assembly which comprises a pneumatic tire and a noise damper made of a spongy material being fixed to an inner surface of the tire, and more particularly, to the assembly for preventing molding failure of the tire without deteriorating adhesion of the noise damper.
2. Background Art
In recent years, there is proposed a pneumatic tire and noise damper assembly which comprises a pneumatic tire and a noise damper made of a spongy material and being attached to the inner surface of the tire. Such an assembly can suppress cavity resonance in the tire cavity, thereby reducing a road noise.
As shown in FIG. 9(A), when the pneumatic tire (a) is vulcanized and molded by a tire mold b, an inner surface (ai) of the tire (a) is pressed by a bladder c which is expanded by charging heat media such as vapor therein. Therefore, an outer surface (ao) of the tire (a) is strongly pushed against the tire mold b, and the inner surface (ai) of the tire is molded by the bladder c. In order to efficiently discharge the air between the tire (a) and the bladders c to the outside, a plurality of vent grooves (not shown) extending in the radial direction, for example, are provided on the outer surfaces of the bladders c. Therefore, as shown in FIG. 9(B), the vent grooves of the bladders c are reversed and transferred on the inner surface (ai) of the vulcanized tire (a) as a plurality of projecting stripes d.
Here, if the noise damper is attached to a region including the projecting stripe d, there is an adverse possibility that the adhesion is deteriorated because the noise damper can not sufficiently fit to uneven surface of the projection d. In order to enhance the adhesion between the inner surface (ai) of the tire and the noise damper, it is proposed to eliminate the vent grooves from the outer surfaces of the bladders c so that the projecting stripes d are not molded on the inner surface (ai) of the tire.
However, if all of the vent grooves are eliminated from the of the bladders c, air between the cavity (ai) and the bladders c can not sufficiently be discharged, and the molding failure of the tire would be produced.